I think the first question is, would you even call this doxing? It clearly touched a nerve or crossed a line, I assume we won't see any more of it.
I'm content to wait and see, assuming there's no actual injury in this case. Doxing is serious. Perhaps even worse considering the context? I don't read into it that much.
Until then, knowing whether or not a moderator exposing user information (regardless of what it is) to indimidate them is considered fair game by the staff would, at the very least, be nice, rule or no rule.
Go back to 4chan.
But thanks for reminding me to update that link in my profile. You should try the greentexting userscript I wrote - I think you'd be surprised at how many HN users actually use > to prefix their quotes. It improves readability quite a bit.
Without any clarification, I think that this sort of thing has a chilling effect on discussion. People will self-censor for fear of being subject to harassment, either by mods or other users.